1520s, "containing or resembling sulfur, of the nature of brimstone," from Latin sulphurosus "full of sulfur," or a native formation from sulfur + -ous. Hence figurative use with suggestions of hellfire (c. 1600). Scientific chemistry sense is from 1790. The spelling with -ph- is standard in Britain. Earlier in the "brimstone-like" sense was sulphureose (early 15c.), and Old English had sweflen. Related: Sulfurously; sulphurously; sulfurousness.